Oracle no longer supports a character mode installer. Therefore, in order to execute runInstaller directly from a console of a machine you are logged into you need to set the DISPLAY environment variable. In the example the name of the node where Oracle is running is called "oracleserver". First, make sure that you also allow runInstaller on "oracleserver" to display X information on your Linux desktop machine. In the example, the computer name where you are running an X Windows desktop like KDE or GNOME is called "yourdesktop". Programs running on remote machines cannot display information to your screen unless you give them the authority to do so.

Before you execute runInstaller, execute xterm (or another terminal client of your choice) to see if your X setup is really working. If you are about to install Oracle on your desktop PC and not on a remote node, then you can skip step 1 and 3.